School of Life Science, East China Normal University, Shanghai, 200062, China.
Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, 200032, China.
Insect Sci. 2021 Dec;28(6):1582-1590. doi: 10.1111/1744-7917.12879. Epub 2020 Dec 3.
Insect growth and development are precisely controlled by hormone homeostasis. The prothoracicotropic hormone (PTTH) receptor, Torso, is a member of the receptor tyrosine kinase family in insects. Activation of Torso by PTTH triggers biosynthesis and release of the steroid hormone in the prothoracic gland (PG). Although numbers of genes functioning in steroid hormone synthesis and metabolism have been identified in insects, the PTTH transduction pathway via its receptor Torso is poorly understood. In the current study, we describe a loss-of-function analysis of Torso in the silkworm, Bombyx mori, by targeted gene disruption using the transgenic CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/RNA-guided Cas9 nucleases) system. Depletion of B. mori Torso (BmTorso) did not eventually affect larval ecdysis and metamorphosis processes. Instead, BmTorso deficiency resulted in significant extension of developing time during larval and pupal stages with increased pupa and cocoon sizes. The ecdysteriod titers in the hemolymph of BmTorso mutants sharpy declined. Transcriptional levels of genes involved in ecdysone biosynthesis and ecdysteroid signaling pathways were significantly reduced in BmTorso-deficient animals. Additionally, RNA-Seq analysis revealed that genes involved in the longevity pathway and protein processing in the endoplasmic reticulum pathway were affected after BmTorso deletion. These results indicate that Torso is critical for maintaining steroid hormone homeostasis in insects.
昆虫的生长和发育受到激素内稳态的精确控制。前胸腺刺激激素（PTTH）受体 Torso 是昆虫中受体酪氨酸激酶家族的成员。PTTH 激活 Torso 触发前胸腺（PG）中类固醇激素的生物合成和释放。尽管昆虫中已经鉴定出许多参与类固醇激素合成和代谢的基因，但通过其受体 Torso 的 PTTH 转导途径知之甚少。在本研究中，我们通过使用转基因 CRISPR/Cas9（成簇的规则间隔的短回文重复序列/RNA 引导的 Cas9 核酸酶）系统，通过靶向基因敲除来描述家蚕 Torso（BmTorso）的功能丧失分析。BmTorso 的耗竭最终并没有影响幼虫蜕皮和变态过程。相反，BmTorso 缺乏导致幼虫和蛹期的发育时间显著延长，蛹和茧的大小增加。血液中的蜕皮甾醇含量在 BmTorso 突变体中急剧下降。参与蜕皮甾醇生物合成和蜕皮甾醇信号通路的基因的转录水平在 BmTorso 缺陷动物中显著降低。此外，RNA-Seq 分析显示，BmTorso 缺失后，与长寿途径和内质网途径中的蛋白质加工相关的基因受到影响。这些结果表明 Torso 在家蚕中维持类固醇激素内稳态至关重要。
